1) Field of the Invention
The field of this invention relates to a method of making border structural members and more particularly to a method of making a plurality of door frames from a single slab of sheet metal.
22) Description of Prior Art
A door frame comprises a part which is utilized as a perimeter structural frame for door assemblies. These frames can be manufactured from many machineable metals such as aluminum, steel and the like. It is even possible to construct the door frame from other than a metallic material such as a hard plastic.
Traditionally, door frames have been manufactured by utilizing a variety of extruded materials, cut to appropriate lengths, with the corner joints mitred and then assembled by utilizing adhesive mechanical fasteners such as rivets, welding and the like. These door frames, because they are not integral, are inherently weak and typically have sharp corners and edges.
A use for a great number of door frames is within aircraft. Within airlines, the normally abusive operational practices of the cabin service personnel cause these frames, that have been assembled in this manner, to bend, twist, crack and finally break, with the corners that have been mitred separating and breaking, creating even sharper edges. These doors within aircraft have become a maintenance headache as well as a safety hazard. It has been discovered that if a solid integral door frame could be manufactured and used in lieu of the door frames that have been constructed of a plurality of assembled parts, that maintenance of such door frames and the safety problems that have been associated with such door frames in the past, are now eliminated. Also, a door frame has been produced that is aesthetically superior.